Counter control circuits



July 17 1951 w. H. BLISS Er AL 2,550,922

COUNTER CONTROL CIRCUITS Filed OCC. 2l, 1949 2 Sheets-Sheryl'I l @Wr-TMWi7] Z Sfr ATTORNEY July 17, ,1951

Filed Oct. 21, 1949 W. H. BLISS El' AL COUNTER CONTROL CIRCUITS 2Sheets-Sheet 2 laan/ln;

INVENTORS MMI/v /76 5.4/55 Jaa@ E @feos of;

ATTORNEY Patented July 17, 1951 ascesi COUNTER CONTROL CIRCUITS WarrenH. liss, and Igor E. Grosdoff, Princeton, N. J., assignors toRadioCorporation of America, accorpcration of Bela-ware Application October2l., 1949, Serialihlo, 122,826

(Cl. ,Z50-27) 3 Claims,

This invention relates to countercontrol'cir cuits and has for itsprincipal object the provision ofan improved' control circuit whichincludes start and stop channels so interconnected with one anotherthat 1) theA application of a start pulse to the start channel iseffective to lock out the start channel and to open the stop channel and(2) the application of a stop pulse to the stopchannel is eiiective tclock out the stop channel. A iur-ther feature is an interlock connectionwhich may be connected so that it is released eithery immediately afterthe application of the start pulsey or: after certain high frequencydecados of the counter havel completed theircount.

More particularly, theimproved control ycircuit includes (l) a pair oftubesY one of which isconnected in the start channel, the other of whichis connected in they stop channel and both of which have two grids andacathode lead resistor andl (2) an interlock4 switch ci the triggercircuit type. having two stable current conducting conditions.

. Associated with theA interlock switch is a manu ally operated' switchwhich conditions the. inter-y lock switch to be preset in either of itscurrent conducting conditions, Under oneof thesefpreset conditions, (l)the application of a start pulse to the tube connected in the startvchannel isl effective to lock out the start channel and to operate the.interlock switch to a condition such that thestop channel is opened and(2) the applicationxof a stop pulse is effective to operate theinterlock switch. tofa condition such'that the stop.

channel is locked out.

Under the other of these preset conditions of' the interlock switch, astop pulse derived from the Figure 2 shows the connectionsk of acircuit` represented'loyI the block I3 of Figure l. This circuit isl oldand is included only to' facilitate an understanding of the circuit ofFigure 3.

Figure 3 shows the connections of the improved control circuit of thepresent invention. In. this figure, the constants of the various circuitcomponentsane indicated by legends placed adjacent to them.

The block diagram of Figure 1 shows a counter including sevendecadesections I!) to it. Each of these decades is similar to that disclosedby a copending application of'lgor E. Grosdoif Serial 2 No. 580,446, ledMarch l, 1945, noW'PatentvNo. 2,521,788, in that it includes fourtrigger circuits which areconnected in cascade and has feedbackconnectionsA such that oney output pulse is deliv- 'ered' for everytenpulses applied to the input of the'decade.

The pulses to be counted are applied' from an input lead Il through aswitch and amplifier I8 tov theinput of the decade I0. The circuitconnections represented by the box I8 are shown in Figure 2 andAaredisclosedin a copending appli' cation of Igor E. Grosdol, Serial No.18,054, -led March 3,0, 1948, now Patent No. 2,545,083 dated March 13,1951.

Operation ci the switch and amplier it is controlled by an interlockandlockout device I9. The connection or the device i9 and its connectionsto other parts of the control circuit are shown in; Figure 3 Asindicated'by FigureZ, the boav It of' Figure 1 represents a circuitwhich includes a-run thyratron 20,5a stop thyratron 2 I, an amplicr 22and a driver tube 23. shown) is connectedl through a lead 2li and acapaci-tor 25- to the grid 25 of theampliiier 22.

The oscillations amplied by the amplifier 22 are applied through acapacitor 21 to the grid `2t of the driver tube23 which has i-ts anode29 con-- nectedthrough av capacitor 3l?v and a lead 3i to' the input ofrtheelecade IIJ of Figurel l.

Whether orno-t the oscillations applied to the grid 28 areitransmitted'to the decade It is determined by the potential oi the grid 32 of thedriver` tube 23.

The potential of the grid 32 is determined by the current conductiveconditions ofthe thyra trons 2li and 2'I. When neither of the'thyratrons is conducting current, the grid 32 and itsr input lead 33areat a potential such that the oscilla tions are blocked by the tube23., When the run thyratron- Z-il is conducting, c-urrentlows througharesistor 3.4 and the potential of the leadtfi is raised toa value suchthat the oscillations are transmitted through'the tube. 2liA to theydecade I t. When both the thyratrons 22' and 2i are conducting, thepotential of the lead 33 is reduced to a value such that the supply ofoscillations through the tube 23 is interrupted.

In the standby condition of the circuit, both the thyratrons arenon-conducting. The supply of oscillations to the counter is started. bythe ap-v plicationof av positive pulse through a lead 35 and a capacitor36 to the grid 3l of the run thyratron 2i) and is stopped by theapplication tor 39 to the grid 40 of the stop thyratron. The thyratrons2i! and` 2 I are reestablished in a nonconductive condition bymomentarily opening a reset switch 4| which connects a +B lead 42 Anoscillator (not 3 through resistors 43 and 44 to the anode of thethyratron 2.

Connected to the anode 45 of the thyratron 20 is a lockout lead 46 whichhas its voltage determined by the voltage drop of the resistors 43 and44. The purpose of this lockout lead will appear in connection with thedescription of Fig'- ure 3.

In the switching circuit of Figure 2 stop tube 2| is interlocked tostart tube 20 since tube 2| cannot fire until after tube 2li has beenturned on. Both of these tubes 2B and 2| lockout individually as soon asthey operate and cannot be operated again until reset switch 4| ismanipulated. Conduction through each of these tubes is continuous fromthe time it is tripped until it is reset.

Other features illustrated by Figure 2 are described in the latter ofthe above copending applications but are not essential to anunderstanding of the present invention which relates more particularlyto the circuit shown in Fig-V ure 3.

Figure 3 shows a thyratron 41 which includes grids 48 and 49 and is madeconductive by a position run pulse applied to the grid 48 through a leadB and a capacitor 5|. When the thyratron conducts, current is drawnthrough resistor 52 and the voltage of the lead 35 is raised to a valuesuch that the thyratron 2li of Figure 2 conducts. When the thyratron 2|)conducts, the voltage of the lead 46,'the grid 4S of the thyra-` tron 41and lead 53 are made more negative. The purpose of the lead 53 will beexplained in connection with the description of another part of thecircuit. The thyratron 41 is operated with its grid 48 at Zero bias andits grid 49 at -3 volts. The voltage of the grid 49 is decreased voltswhen the runf thyratron 2U of Figure 2 conducts. This prevents furtheroperation of the thyratron 41.

A positive pulse for stopping the supply of oscillations to the decadeIl) is applied from a lead 54 through a capacitor 55 to a grid 56 of athyratron 51. As a result, a sharp positive polarity pulse is developedon lead 38 from the upper terminal of cathode lead resistor 58 and thestop thyratron 2| is made to conduct. For a purpose to be explained, anegative pulse is applied from the lower terminal of anode lead resistor59 through a capacitor (il to a lead El?.

The thyratron 51 is operated with its grid 56 at zero bias. The voltageof its grid 62 is derived from the anode 63 of a trigger circuit switchMV| and has a value of l0 volts when current conduction is not throughthe anode 63 and a value of 40 volts when current conduction is throughthe anode 63. The anode 63 is also connected through resistors 64 and 65to a lead 66 which is connected to the grid of the last stage of thestop signal input channel as hereinafter described.

The purpose of placing start and stop tubes 41 and 51 in tandem with andahead of similar tubes 20 and 2| is to prevent erroneous pulses fromgetting from the start and stop pulse sources to driver tube 23. Whenstart and stop tubes 20 and 2| only are used it is possible byinter-electrode capacity to pass pulses through these tubes even afterlockout.

Gas tubes 41 and 51 are operated in a selfrestoring circuit and do nothave to be reset. For example when tube 41 is triggered it quicklydischarges condenser 9|. When the voltage of condenser 9| has droppedsufficiently, conduce tion through tube 49 ceases for lack of voltage tomaintain ionization of the gas.` Condenser 9| then recharges throughresistor 9U. Lockout is aiiected in these tubes by depressing thevoltage of No. 2 grid to a sufficiently negative value.

The switch MVI, hereinafter called the interlock switch, is a, triggercircuit of the type which includes a pair of triodes 651-52-68 and63-69-68, the cathode 68 being common to the two triodes. The triodeshave operating voltage to their anodes from a +225 volt lead through acommon resistor 10 and separate resistors 1| and 12, have their commoncathode 68 connected to ground, and have their anodes eachcrossconnected to the grid of the other through a resistor which isshunted by a capacitor. A'bias potential of -67 volts is applied througha lead 13, an interlock on-off switch 14 and a resistor 15 to the grid52. A similar bias potential is applied to the grid 69 from the lead 13through a reset switch 16, a lead 11, the switch 14 and a resistor 18.

AS is well known, momentary opening of the switch 16 is elective toestablish current conduction in the anode 63. Current conduction isstable in either one or the other of the anodes 61 or 63 and istransferred from one to the other' either in response to the applicationof a positive pulse to the grid of the triode which is not conducting orin response to the application of a negative pulse to the grid of thetriode which is conducting.

The switch MV can be reset to either current conducting condition by theswitch 14, If it is preset with current conduction in the anode 63, thethyratron 51 is biased oi and a stop pulse applied to the lead 54 isineffective to interrupt the supply of oscillations to the decadev l).With current conduction 'through the anode 51, however, the tube 51 isin condition to transmit the stop pulse to the grid 4|! of the stopthyratron 2| of Figure 2.

The lead 53 is connected through a switch 8i) and a capacitor 8i to thegrid 65 of the switch MVI. As previously indicated, this lead 53 is connected through a lead 46 to the anode 45 of the Start or run thyratron20 of Figure 2 and is at 3 volts when neither of the thyratrons 2li or2| is conducting, at -20 volts when the thyratron 20 is conducting, andat -50 volts when bothfZlJ and 2| are conducting.

The purpose of switch 8B is to allow for eitherv immediate or delayedrelease oi interlock. When Vswitch 8i] is closed as shown, the passageof a start pulse causes lead 46 to suddenly drop in potential and tripinterlock multivibrator MVL 'Ihis causes conduction in the right handside of MV| to cease and the No. 2 grid of tube 51 is brought up to thepoint where it can be trig gered.

When switch 8|) is open the tripping of .M 'VI is delayed until a pulseis received on lead 83 frorn decade I2 of Figure 1.

The grid 69 is also connected through a capactor 82 and a lead 83 to theoutput of the l0() kc. decade |2 of Figure 1. When the decade |2completes its rst cycle of operation, its output is applied to the grid59.

The stop pulse applied to the lead 54 is derived from the upper terminalof a resistor B4' which is connected in the cathode lead of a tube 85which is the last stage of the channel through which the stop pulse isapplied. Such stop pulse is applied through capacitors 86, and 31` tothe grids 63 and 8@ oi the tube 85. The grid 89 is biased to zero voltsand the bias voltage of grid 88 is either -10 or -40 volts depending onthe current conductive condition of the switch MVI. With the anode 63conducting, the voltage of the grid 88 is -40 volts which is suilicientto prevent ring of the tube 85. Approximately 140 microseconds after theapplication of the run or start pulse, current conduction shifts to theanode 61 of the interlock switch, the voltage of the grid 88 is changedto -10 volts, and the tube is in condition to transmit a stop pulse tothe lead 54.

Assuming current conduction to be in the anode 63 as indicated by thearrow, the application of a start pulse to the lead 50 of Figure 3results in energization of the start thyratron of Figure 2 and theapplication of a negative pulse to the grid 69 by which currentconduction is shifted to the anode 61. With no current owing through theresistor l2 and the anode 63, the tubes 51 and 85 are in condition totransmit a stop pulse. When such stop pulse is applied, the tubes 51 and85 conduct and there is applied from the anode of the tube 51 to thegrid 62 of the switch MVI a negative pulse by which current conductionis returned to the anode 63.

Under these conditions the tubes 41 and 51 are individually locked outso that they are non-receptive to any further signals that may come overthe start and stop channels.

Instead of locking out the stop pulse by the tube 51 as explained above,it may be locked out by a positive pulse applied from the output stageof the decade l2 of Figure 1, such positive pulse being appliedA throughthe lead 83 and the capacitor 82 to the grid 69 of the interlock switchMVI. y This interlock functions in a manner similar to the lockoutbetween the tube 28 of Figure 2 and the switch MVI and tube 51 of Figure3 except that it prevents operation of the stop channel during the 100micro-seconds of timing.

The interlock switch MVI is required for single line operation but maybe made ineffective by the switch 14 when the time interval to bemeasured is shorter than 100 micro-seconds. Thus with the switch 14closed to the right, the

switch MVI is preset with current conduction` in the anode 63, theeffect of the positive pulse applied to the grid 69 through the lead 83is neutralized by the negative voltage of the lead 53 and the stop pulseis locked out only in response to the application of a stop pulse to thelead 54 of Figure 3 as previously explained.

What the invention provides is a counter control circuit including startand stop channels which are so interconnected that the stop channel islocked out until a start pulse has been applied to the input of thestart channel. The interconnections between these/y two channels is suchthat the start channel is locked out and the stop channel is opened inresponse to the application of a start pulse. The application of a stoppulse, either to the input of the stop channel or from a predeterminedstage of the counter, is elective to terminate the counting of thecounter and to lock out the stop channel.

What is claimed is:

1. In a circuit for controlling the supply of constant frequencyoscillations to a counter, the combination of a normally open startchannel, a normally blocked stop channel, means connected in said startchannel and responsive to a start pulse applied to said start channelfor applying a lockout voltage to said start channel, an interlockswitch connected to said stop channel and responsive to said lockoutvoltage for opening said stop channel, and means connected between saidstop channel and said switch for blocking said stop channel in responseto the application of a stop pulse to said stop channel.

2. In a circuit for controlling the supply of constant frequencyoscillations to a counter, the combination of a normally open startchannel, a normally blocked stop channel, means connected in said startchannel and responsive to a start pulse applied to said start channelfor applying a lockout voltage to said start channel, an interlockswitch connected to said stop channel, means for applying said lockoutvoltage to said switch for opening said stop channel, means connected'between said stop channel and said switch for blocking said stopchannel in response to the application of a stop pulse to said stopchannel, and means for alternatively applying an output voltage from astage of said counter to said switch for opening said stop channel.

3. In a circuit for controlling the supply of constant frequencyoscillations to a counter, the combination of a normally open startchannel, a normally blocked stop channel, means connected in said startchannel and responsive to a start pulse applied to said start channelfor applying a lockout voltage to said start channel, an interlockswitch connected to said stop channel. means connected between an outputstage of said counter and said switch, and means for operating saidswitch to a condition such that said stop channel is blocked until apulse is applied to said switch from said output stage.

WARREN H. BLISS. IGOR E. GROSDOFF.

REFERENCES CITED The following references are of record in the

